Current transformer calculations

[Mondy]

Can anyone help me with the accurate calculation of ratio and phase errors in measuring current transformers?

I would like to get a spreadsheet or something similar together for the design of toroidal bushing transformers and so far have not come up with any equations or methods that agree with test data that I have on actual current transformer test results. Some help from you experts would be very much appreciated.

Thanks
Ray

 

[Mondy]

Is there anyone that can help me as I really could do with some assistance?

Cheers
Ray

 

[DanDel]

What percentage of error do you expect? I understand that the phase error in a CT is on the order of 10-15 minutes (much less than 1 degree).

 

[Mondy]

Hi Dan

Thanks for your reply It is appreciated.

Yes you are correct the phase angle error is very small in most measuring CTs and should be only a few minutes. I need some help if possible with the equations used in calculating the ratio and phase angle errors in measuring CTs as all the examples that I have seen I have tried and they do not match up with sample test data that I have.

The current ratio error varies with such things as secondary resistance, burden power factor etc and both ratio and phase angle errors are calculated from the working flux and the core material magnetic properties. I have the core material data but I cannot get the "usual" calculations to work. Do you or anyone have any experience of suitable equations etc?

Cheers
Ray